Changing perspectives in screening for congenital hypothyroidism and congenital adrenal hyperplasia.

Purpose Of Review: The purpose of this review is to summarize recent information that has had a significant impact on the laboratory diagnosis and clinical management of newborns with congenital hypothyroidism and congenital adrenal hyperplasia (CAH).

Recent Findings: An approximate doubling of the incidence rate of congenital hypothyroidism in many parts of the world has been attributed to increased detection of infants with mild disease, delayed thyroid stimulating hormone elevations and demographic changes. A substantial number of children with modest thyroid stimulating hormone elevations on screening have permanent disease.

The increased incidence of congenital hypothyroidism: fact or fancy?

Objective: The incidence of congenital hypothyroidism (CH) detected by newborn screening in the US has increased significantly since the early 1990s. We defined the characteristics associated with the increased incidence.

Patients: A cohort of children with CH born during an earlier period of low incidence (1991-94) was compared with a cohort born during a later period when the incidence of CH had doubled (2001-04).

Congenital hypothyroidism with a delayed thyroid-stimulating hormone elevation in very premature infants: incidence and growth and developmental outcomes.

Objective: To test the hypothesis that very low birth weight (VLBW) and extremely low birth weight (ELBW) infants have an increased incidence of congenital hypothyroidism (CH) with a delayed thyroid-stimulating hormone (TSH) elevation and that the outcomes of these infants are similar to control infants.

Study Design: Retrospective analysis of newborn thyroid screening data for 92 800 live births in Rhode Island to identify CH with a delayed TSH elevation. Developmental, growth, and endocrine outcomes of the index cases were assessed at 18 months corrected age.

Neonatal thyroxine, maternal thyroid function, and child cognition.

Context: Thyroid hormone is essential for normal brain development. Limited data are available regarding whether thyroid function in neonates influences later cognitive development.

Objective: Our objective was to study associations of newborn T4 levels with maternal thyroid function and childhood cognition.

Iodine supplementation for pregnancy and lactation-United States and Canada: recommendations of the American Thyroid Association.

The fetus is totally dependent in early pregnancy on maternal thyroxine for normal brain development. Adequate maternal dietary intake of iodine during pregnancy is essential for maternal thyroxine production and later for thyroid function in the fetus. If iodine insufficiency leads to inadequate production of thyroid hormones and hypothyroidism during pregnancy, then irreversible fetal brain damage can result.

Thyroid peroxidase antibodies in dried blood specimens of newborns.

Previous studies have disclosed that a substantial percentage of infants from mothers with thyroid autoimmunity have antibodies to thyroid peroxidase (TPOAb) at birth. Furthermore, these antibodies have been shown to be of maternal origin. In view of this we thought it would be of interest to determine the prevalence of TPOAb in newborns from an unselected population of women.